Learn how to shape metal
Alan (Cornish) learns to love The English Wheel. English Wheel none too sure about him though
SKILLED OPERATORS of English wheels are held in some reverence in the engineering community. Forming sheet metal on these machines into compound-curved panels is a curious mix of art and engineering requiring a good deal of skill and an understanding of both. How do these magicians of metal and sorcerers of sheet achieve the voluptuous curves in their work? Alan Woodward of Specialized Products is a man who knows and he agreed to give us a few insights.
It’s hard to relate a 16swg aluminium sheet with the Egli Vincent banana tank Alan is showing us as demonstration of his skill. Harder still to link its smooth curves with the mute jaws of the massive English wheels on which Alan works his craft. The machine itself is of uncertain vintage, although Alan says, “It’s probably 1940s.” It was bought secondhand by his father Don when he set up Specialized Products in the 1960s, has survived a workshop inferno and faithfully formed metal for many thousands of hours over the decades. The top curve of the wheels’ cast iron frame bears the legend ‘George Kendrick Ltd., Birmingham’, a now dissolved concern that supplied English wheels to a good many coachbuilders and workshops. Before we get to work with the wheels themselves, Alan has to cut out a piece of sheet aluminium to a pattern established by his father when he first added Egli tanks to his extensive repertoire. Wielding the tin-snips and cutting through the ally with the ease of a tailor running shears through some woollen
pinstripe, Alan imparts a tip which, if we learn nothing else today, will surely prove invaluable. “Keep the top blade of the snips flat to the workpiece,” he says, “that way you won’t wind up with an edge like a serrated bean can top.” Indeed the cut sheet’s edges are so smooth you almost think you could work it without gloves. Not that you would [see pic, right... – JM].
Alan drills holes where the middle of the tank filler will eventually go, and the end of the recess for the headstock. “You’d never be able to figure it out later,” he says.
The next preliminary is cleaning the wheels. “Aluminium marks very easily on the wheels and it’s a nightmare to remove any pits and scratches,” he says. To demonstrate the point he takes a hair, puts it on a piece of scrap sheet and rolls it through the wheels. The aluminium now has a furrow in it deep enough to catch a fingernail. “That’s why the wheels have to be scrupulously cleaned before, during and after,” he says, setting to with a nylon abrasive pad and then a rag.
While he’s at it we enquire whether the wheels themselves have particular names. “Top wheel, bottom wheel,” he grins, indicating the top and indeed the bottom wheel. “They’re also called the rolling wheel and the anvil wheel, and the contact area between the two is the ‘blow’ as in hammer blow. If you think of the English wheels in terms of beating out sheet with a planishing hammer on a sandbag, then the bottom wheel is effectively the hammer. The amount of pressure or ‘weight’ on the contact area is determined by the foot adjuster which closes the gap between the wheels.”
Placing the buck for the Egli tank on the bench for reference, Alan dons his gloves
“You’ve buggered that up,” says Alan, as he’s handed something that looks more like it’s been run over by a tractor wheel”
and picks up the cut aluminium sheet. Inserting it between the wheels he kicks a bit of weight on with the screw wheel and gives the metal a few passes. “You have to give it long strokes and don’t get too close to the edges or you’ll take the curves out as quickly as you put them in,” he advises as he works. “By adding weight you make the gap between the wheels narrower than the thickness of the metal. This allows the metal to be stretched to form compound curves or what I call ‘shape’. If you were working only in one direction you’d be simply
making a bend and the metal wouldn’t need to be stretched. Too little weight and you’ll be there forever, too much and you will have more shape than you’re after.”
In the absence of gauges on this wholly manual machine, how much weight is just right we wonder. “You get a feel for it,” says Alan, “have a go.” What, already? And on a piece of sheet intended for an actual tank? “I don’t want to bugger it up,” I say. “You won’t bugger it up,” says Alan, “I’m off to cut the sheet for the other panels.”
Here goes nothing. Although inert, the English wheels seem to be possessed of a mind of their own. The sheet veers to the opposite side from that which I’m intending to steer it towards. The wheels skitter close to the edge of the metal and sometimes beyond, defying all attempts to haul it back on course. The long easy strokes Alan managed seem impossible with any amount of weight applied, and even to the untutored eye the marks left where the strokes have stopped and started don’t look like part of the desired result.
“You’ve buggered that up,” says Alan, as he’s handed something that looks more like it’s been run over by a tractor wheel than formed in English wheels when he returns with the other pieces of cut sheet. However the buggeration is not total. Alan removes excess shape by wheeling the edges and the stop/start marks disappear with a little more effort. “You have to keep the panel flowing and work it as a whole. Tell the metal where to go. Overlap the blows to avoid forming ridges and the lines must follow through to get any ridges and defects out. Use a little less weight close to the edges too to keep things smooth,” he says as he rectifies the mistakes.
Confident I’ve learned my lesson, he lets me have another go. The improvements are instant and placing the panel over the buck, it’s close to the required shape.
Alan bends up one of the sides for the tank, undertaking all the work on that himself as he’d like this tank to be done before the mercury drops in Hades.
He then reprises the aluminium gas welding masterclass from a couple of issues ago to join the two panels. The English wheels will then be deployed to smooth out the weld like those you can see on the completed tank.
“It’s immensely satisfying to get this from a flat sheet of metal,” he says. “English wheels demand concentration and you need to learn to understand the metal. For me it’s all about persistence, otherwise I would have got a proper job years ago.”
But who wants a proper job when you can be an artist?
Let’s be fair to the boy. Alan W actually used Alan S’s work on a customer’s tank.
Drooling in anticipation of a hard job half-done
Two Alans: both questioning the concept of transferable skills
Keep the snips at 90˚ for a clean cut
Watch and learn. Do and struggle. It ain’t easy It fits where it touches. Not a bad effort Welds go into the wheels to be flattened Thing of beauty and 35 hours’ worth of graft Alan W works his magic with torch and rod FINISHED